<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul {

            display: flex;
            width: 600px;

            margin: 0;
            padding: 0;
        }

        li {
            box-sizing: border-box;
            flex-grow: 1;
            list-style-type: none;
            background-color: brown;
            /* overflow: hidden; */
        }

        li:first-child {
            /* flex-basis: 101px; */
            /* width: 101px; */
        }

        div {
            background-color: gray;
            width: 250px;
            height: 200px;
        }
    </style>
</head>

<body>
    <ul>
        <li>
            <div></div>
        </li>
        <li>
            <div></div>
        </li>
        <li>
            <div></div>
        </li>
    </ul>
</body>

</html>